Dietary fiber or roughage is the indigestible portion of food derived from plants. The consumption of foods high in fiber has been found to reduce appetite. Dietary fiber is made up of soluble and insoluble fiber. Soluble fiber, which dissolves in water, is readily fermented in the colon into gases and physiologically active byproducts and can be prebiotic and viscous. Insoluble fiber, which does not dissolve in water, is either metabolically inert and provides bulking or can be prebiotic and metabolically fermented in the large intestine.
Dietary fibers can act by changing the nature of the contents of the gastrointestinal tract and by changing how other nutrients and chemicals are absorbed. Some types of soluble fiber absorb water to become a gelatinous, viscous substance which is fermented by bacteria in the digestive tract. Some types of insoluble fiber have bulking action and are not fermented. Lignin, a major dietary insoluble fiber source, may alter the rate and metabolism of soluble fibers. Other types of insoluble fiber, notably resistant starch, are fully fermented.
Chemically, dietary fiber consists of non-starch polysaccharides such as arabinoxylans, cellulose and many other plant components such as resistant starch, resistant dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans, and oligosaccharides. A novel position has been adopted by the US Department of Agriculture to include functional fibers as isolated fiber sources that may be included in the diet. The term “fiber” is something of a misnomer, since many types of so-called dietary fiber are not actually fibrous.
Food sources of dietary fiber are often divided according to whether they provide predominantly soluble or insoluble fiber. Plant foods contain both types of fiber in varying degrees, according to the plant's characteristics.
Advantages of consuming fiber are the production of healthful compounds during the fermentation of soluble fiber and insoluble fiber's ability (via its passive hygroscopic properties) to increase bulk, soften stool, and shorten transit time through the intestinal tract.
Often dietary fiber compositions are used in the food or consumer product industry for their functional properties that include viscosifying, water absorbing, bulking, emulsifying and even gelling properties. The addition of a functional dietary fiber can provide textural benefits, nutritional benefits, and in some cases simpler labels replacing less consumer friendly options.
Some plants contain pectin as the soluble fiber component. Pectin is a polysaccharide useful as a colloidal in many applications such as food products, beverages, personal care products, pharmaceuticals, and detergents. Typically, pectin is commercially recovered in its water soluble form from a pectin-containing biomass material by extraction.
Unfortunately, the pectin extraction process is often harsh resulting in the degradation of the quality of pectin measured as intrinsic viscosity. Pectin with a higher intrinsic viscosity is often desirable because high intrinsic viscosity indicates that the extracted pectin is closer to its original state in the raw material and therefore has not been degraded during the extraction process. From a cost optimization perspective, the extraction process should be designed to extract the greatest amount of pectin available from plants, but pectin yield is often limited in exchange for pectin quality. Further, processing of plants is also challenging due to the proclivity of pectin to bind with water.
Thus, there remains a need for providing a dietary fiber from pectin-containing plants that can be processed with ease and retain both soluble and insoluble fiber components with high quality properties.